Stevecham
When used correctly, the playing surface of the record is flat to the platter and not dished.
Ditto. I've never had an issue with using the clamp with the rubber washer. The washer will compress plus the label area of the platter is recessed so I'm not sure why your records would be dished. The clamping works perfectly with flat records, and helps with warped records significantly. Add the VPI periphery ring and only badly warped records across the surface will be noticeable.